Design doc: bit.ly/v8-repl-mode
This CL adds a new REPL mode that can be used via
DebugEvaluate::GlobalREPL. REPL mode only implements re-declaration
of 'let' bindings at the moment. Example:
REPL Input 1: let x = 21;
REPL Input 2: let x = 42;
This would normally throw a SyntaxError, but works in REPL mode.
The implementation is done by:
- Setting a 'repl mode' bit on {Script}, {ScopeInfo}, {ParseInfo}
and script {Scope}.
- Each global let declaration still gets a slot reserved in the
respective {ScriptContext}.
- When a new REPL mode {ScriptContext} is created, name clashes
for let bindings are not reported as errors.
- Declarations, loads and stores for global let in REPL mode are
now "load/store global" instead of accessing their respective
context slot directly. This causes a lookup in the ScriptContextTable
where the found slot for each name is guaranteed to be the same
(the first one).
Bug: chromium:1004193, chromium:1018158
Change-Id: Ia6ab526b9f696400dbb8bfb611a4d43606119a47
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1876061
Commit-Queue: Simon Zünd <szuend@chromium.org>
Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Cr-Commit-Position: refs/heads/master@{#64793}
